What the Hell

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Philip Ball has a Ph.D. in physics from the University of Bristol in England and was an editor at Nature for more than 20 years. He is the award-winning author of 15 books, including The Music Instinct: How Music Works, and Why We Can’t Do without It.

C H E M I ST R Y

Many of the most profound scienti c questions—and some of humanity’s most urgent problems—pertain to the science of atoms and molecules

By Philip Ball

How Did Life Begin?

the first living beings arose from inanimate matter almost four billion years ago is still shrouded in mystery. How did relatively simple molecules in the primordial broth give rise to more and more complex compounds? And how did some of those compounds begin to process energy and replicate (two of the defining characteristics of life)? At the molecular level, all of those steps are, of course, chemical reactions, which makes the question of how life began one of chemistry.

The challenge for chemists is no longer to come up with vaguely plausible scenarios, of which there are plenty. For example, researchers have speculated about minerals such as clay acting as catalysts for the formation of the first self-replicating polymers (molecules that, like DNA or proteins, are long chains of smaller units); about chemical complexity fueled by the energy of deep-sea hydrothermal vents; and about an "RNA world," in which DNA’s cousin RNA—which can act as an enzyme and catalyze reactions the way proteins do—would have been a universal mole-

cule, before DNA and proteins appeared. No, the game is to figure out how to test these ideas in reactions coddled in the test tube. Researchers have shown, for example, that certain relatively simple chemicals can spontaneously react to form the more complex building blocks of living systems, such as amino acids and nucleotides, the basic units of DNA and RNA. In 2009 a team led by John Sutherland, now at the MRC Laboratory of...